Anthraquinone based natural pharmaceutical molecules enabling high-performance aqueous organic redox flow battery via hydrogen bonding induction

Aqueous organic redox flow batteries (AORFBs) have the potential to facilitate large-scale energy storage, which is expected to solve the inherent problems of indirectness and unsustainability of renewable energy sources such as solar and wind energy, and integrate them into the power grid. Redox-active anthraquinone molecules have the potential to serve as effective anolyte materials for AORFBs. Hydrogen bonds play an important role in the structural stability of molecules. Modulation of the hydrogen bonding effect in the electrolyte can lead to the attainment of enhanced performance in batteries. Here, we report a commercially available anthraquinone natural pharmaceutical molecule that achieves high-performance aqueous organic redox flow batteries through hydrogen bonding induction. Cyclic voltammetry reveals that excessive electron-donating substituents compromise the electrochemical stability of anthraquinone derivatives. Around 0.1 M Rhein||K 4 [Fe(CN) 6 ] battery exhibit near 100% Coulombic Efficiency (CE) and high Energy Efficiency (EE) greater than 86%, with capacity decay decreasing from 0.124% per cycle to 0.06% per cycle and 0.3 M Rhein||K 4 [Fe(CN) 6 ] battery decreasing from 0.47% per cycle to 0.11% per cycle due to Rhein and NH 4 OH forming hydrogen bonds, effectively mitigating Rhein's capacity degradation. A new method for achieving low-cost, low-capacity decay, and high energy efficiency anthraquinone active materials is established.